Temperature-responsive switch mounting and installation



Dec. 4, 1956 1 L. vERKulL 2,773,153

TEMPERATURE-RESPONSIVE SWITCH MOUNTING AND INSTALLATION Filed Oct. 3,1955 2 Sheets-Sheet 1 A al; TS

5 la Ts C f 0 l 26 t* f2 2 0 53 3l cn Bmetullc ATTORNEY Dec. 4, 1956 1 1VERKUH. 2,773,153

TEMPERATURE-RESPONSIVE SWITCH MOUNTING AND INSTALLATION Filed Oct. 3,1955 2 Sheets-Sheet 2 FIG@ INSULATION 4425 I |2356 Noi?? 21 |38 I7V V j|o l i 52 27C |l Il 28 52 FIG INVNToR. Leo L..Verkui| 19A/mmm ATTORNEYUnited States Patent TEMPERATURE-RESPONSKVE SWITCH MOUNT- ENG ANDINSTALLATION Leo L. Verkuii, Norwalk, Conn., assigner to EdwardsCompany, Inc., Norwalk, Conn., a corporation of Flew York ApplicationOctober 3, 1955, Serial No. 538,14@

S Claims. (Cl. 20G-138) This invention relates to the housing, mountingand installaltion of temperature-responsive elec-tric switches`particularly such as are to form part of re alarm or detector circuitsor systems for the interiors of buildings, houses, and the like,

ln such systems, thermostatic switches, in suitable number, areinstalled at suitably distributed locations and are suitablyinterconnected electrically to a suitable alarm or signal-transmittingdevice which is caused to be actuated when any one or more of thethermostatic switches responds to rise in temperature, in the buildingkarea `or space in which it is located, sufficient lto actuate theswitch; such switches are usually located at or near the ceiling andusually are constructed or set to have different temperature-responsiveratings, such las 140 F., 180 F., or 200 F., for in some interiorlocations la switch of higher temperature response is appropriatelyemployed while other spaces require switches of lower temperatureresponse. Also, the circuits of such -systems are operable, according tocircumstances, at different supply vvoltages, usually derived from thebuilding or house lighting circuit and, ywhere the latter is analternating current circuit, `a step-down transformer is usuallyemployed to obtain the desired voltage for which the particular systemis constructed or rated.

One of the objects of this invention is to provide a thermostatic switchand housing that will be of compact and reliable construction and`assembly and well adapted for ease `and facility of installation, as inre detecting systems of the abovementioned character. Another object isto provide a simple and practical thermostatic switch and housing ormounting therefor having coacting features of construction to facilitatemanufacture and assembly and that will facilitate, in uncomplicatedrnanner, installation according to various needs or requirements metwith.

Another object is to provide a thermostatic switch mounting andinstallation capable of wide `and dependable flexibility ofrearrangement or assembly, in the eld, to meet various types orstandards of wiring, such as lowvoltage exposed wirng, surface wiringsuch `as armored, sheathed, or conduit-contained wiring, concealedwiring of the just-mentioned types, and the like. Another object is toprovide a thermostatic switch mounting and installation capable of suchflexibility of rearrangement or assembly, in the held, `so that,according to need, the thermostatic switch and mounting may be direc-tlysurfaceinstalled as on a :ceiling or a wall, or assembled interiorly ofa `wall box particularly where hush-mounting is desired or required, orassembled exteriorly of a -wall box or outlet box, all in va manner tomeet the safety requirements or standards particularly Vith respect tovarious magnitudes of voltage of the circuit of the detector system.Another object is to provide a construction of the justmentionedcharacter in ywhich dependable provision is made for maintainingvisible, for whatever rearrangement or assembly of the parts iseffected, suitable indicia rice identifying the technical lrating orother data as is or may be required, in systems of `the above-mentionedcharacter, -by such lauthorities as the Board of Fire Underwriters.

Another object is to provide a thermostatic switch and housing ofnonmetallic material and a mounting therefor of metallic materialcoactingly adapted for flexibility of assembly in variousinterrelationships -according to need while maintaining suitable safetyfactors of insulation and the like for lthe resultant assemblage and`the wiring leading therethrough to the thermostatic switch.

Another object is to provide a thermostatic switch subassembly adaptedfor direct installation with its thermostatic element presented forthermal response and an outlet box element to form therewith anassemblage with the `sub-'assembly selectively either within the box oroutside of the box and in either case with the thermostatic elementlproperly presented for thermal response Ifrom the outside of the box.Another object is to carry out the just-mentioned object in which theseveral parts are adapted for selective coaction, according tothe methodof assembly, to provide safety of wiring to the switch.

Another object `is in general to provide improved constructions andinstallations of thermostatic switches, particularly to meet the diverserequirements of various kinds and types of wiring, in fire detectorsystems of the above-mentioned type, for bo-th existing buildingstructures and structures in course of construction. Other objects `willbe in part obvious or in part pointed out hereafter.

The invention accordingly consists `in the features of construction,combinations of elements, and arrangements of parts as will be exempliedin the structure `to be hereinafter described and the scope `of theapplica-tion of ywhich will be indicated inthe following claims.

In the accompanying drawings in which a preferred embodiment of theinvention is shown by way of lllustration and in which similar referencecharacters refer to similar parts throughout the several views,

Figure l is an elevation, as seen looking upward, of a `thermostaticswitch and housing sub-assembly as it appears when installed, as on aceiling or over-head beam or the like;

Figure 2 is an end elevation `as seen along the line 2 2 of Figure l;

Figure 3 is a vertical sectional View, on an enlarged scale, as -seenalong the line 3-3 of Figure l;

Figure 4 is an elevation, as seen looking upward, of `an installation inwhich the sub-assembly -of thermostatic switch and housing and a plateelement of a wall box yare arranged and coact for substantiallyconcealed mounting with the thermally-responsive element of thethermostatic switch positioned substantially tlush with the plane of theceiling;

Figure 5 is a transverse sectional View, on an enlarged scale and withcertain parts broken `away `to conserve space, as seen `along the line5-5 of Figure 4;

Figure 6 is an elevation, as seen looking upward, of Ian installation inwhich the thermostatic switch and housing sub-assembly and the plateelement of the outlet box are rearranged and for wiring and mountingwith the sub-assembly external of the wall box;

Figure 7 is a transverse section, on an enlarged scale and with certainparts broken `away to lconserve space, `as vseen lalong the line 7--7 ofFigure 6, illustrating also that the wall box may be surface-mounted;

yFigure 8 is an elevation as seen along 'the line 8--8 of =Figure 2,showing in rear `elevation certain parts of the sub-assembly and,partially broken away, an insulating rear terminal cover plate; and

Figure 9 is an elevation of the rear terminal cover plate alone.

While, so far as other features of my invention are con cerned, thethermostatic switch may take other forms than that described, itpreferably is constructed in the form of a compact unit adapted for easyassembly to other parts and provided with a thermally-responsive elementthat is birnetallic and preferably in the form of a concaveconvexbimetallic snap-acting disk so vas to present a suitable area thereoffor thermal response to the atmosphere of the building space or room inwhich it is to be installed in a tire detection or alarm system. In thedrawings, I have designated this preferred form of thermostatic switchunit, as a Whole, by the reference character TS, and its construction ingeneral is better shown in Figures 3 and 8.

Turning rst to Figure 3, the thermostatic switch unit TS comprises 'acup-like casing l0 of insulating material, such as lany of the moldableplastics, of round cross-section provided at its open end with anexternal tiange l1 and having seated across its open end the snap-actingbimetallic disk l2 which is secured in position by a metallic ferrulespun over the flange ll and the peripheral portion of the disk l2. Asshown in Figure 3, the bimetallic disk 12 may be constructed, orassembled to the casing l0, so that in its normal bowed condition orshape, its convexity is toward the bottom end of the casing llt) and,upon rise in temperature, it reverses its bowed shape, doing so with asnap action as above mentioned.

Such bimetallic disks are well-known as are also various contact-makingand contact-breaking arrangements to respond to this snap action formaking or breaking the electrical circuit in which the thermostaticswitch is connected; accordingly, any such suitable arrangement may beembodied within the cup-like casing l for co-action with the bimetallicdisk l2 and need not be shown or described in detail. In Figure 3 l havetherefore simply indicated such an internal circuit maker or breaker bythe broken-line rectangle 14, its parts being electrically connected, inknown manner, to two terminal and mounting lugs -5 of at sheet-metalstock set into and suitably secured at the external face of the bottomof the molded casing l0 (see also Figure 8) so that they project on adiameter and in opposite directions from the casing l0, being provided,in their projecting portions each with a Suitable hole for coaction withmounting and connecting screws `as later described.

The parts thus far described comprise the illustrative form which thethermostatic switch unit TS preferably takes; it may be embodied indimensionally small and compact form. For example, the bimetallic diskl2 may have a diameter on the order of The thermostatic elementillustratively in the form of bimetallic disk 12, may be constructed orset, in Icoaction with the internal switching mechanism 14, to have anysuitable temperature-responsive rating, such as 140 F., 180 F., or 200F., and in the tire detection system in which these thermostatic switchunits are to be installed, the system can oftentimes include units ofdifferent temperature responses according to the different character ofthe respective rooms or spaces or areas, of the building, in which theyare located. It is desirable, therefore, that the respective ratings,and other technical information, pertinent to each installed unit bealways visible, even though the type or form of electrical wiring or ofinstallation of the unit vary widely, within authorized standards, andthus also dependably comply with requirements for visible identifyingand rating data.

In old as well as in new building construction, various types orstandards of wiring are permissible, a factor of consideration includingthe voltage at which the tire detection circuit or system is to operate.For example, in a low-voltage system, on the order of 2S volts, thethermostatic switch unit, such as the unit TS, may be surfacemounted, asby mounting it on the ceiling or other overhead structure, and thecircuit conductors, appropriately insulated for such lower voltages, maybe run along and secured to similar surfaces. On the other hand, wherethe detector circuit is to operate at higher voltages, or for otherreasons, the thermostatic switch unit is to be associated with a wallbox, outlet box, or the like, with associated standards of wiring, andthe box may be surfacemounted or flush-mounted, and in either case thethermostatic switch unit may, for various reasons, be mounted externallyof the box or internally thereof. These varying conditions illustratesome of the variables met with in building structures, old or new orunder construction, in installing tire alarm or detector systems, andone of the dominant aims of this invention is to provide practical andsimple means for safety and dependably meeting such varyingrequirements.

in Figures 4 and 5 and Figures 6 and 7 I have shown two of severalpossible forms of installation requiring the use of a box, such as anoutlet box, wall box, or the like, with which, for mounting and wiringpurposes, the thermally-responsive switch, for re detection, is to beassociated, thus also to facilitate the use of such kinds or standardsof house wiring or building wiring as may be desired or needed. Thelatter are available in various forms of construction, such asnon-metallic sheathed cable or conductor, metallic sheathed conductor,conduitcarried wires, and others, and for that reason such types ofwiring are not shown in the drawings. The box shown in Figures 5 and 7is generally indicated by the reference character B and may make anysuitable or desired form of which also many are known; for purposes ofillustration, the box B may comprise a standard type of outlet boxhaving a usually flat bottom 17 and integral side wall 18 which may becircular or polygonal in cross-section, being provided with threadedinwardly projecting diametrically opposed lugs 20--20 (Figures 5 and 7)and screws 21-21. As is usual, the bottom 17 or the side wall 18 or bothis provided with knock-outs 22 through which, when removed, the circuitwiring is brought into the box, in the manner known in the art.

To meet varying requirements such as those indicated above, I provide anumber of parts that are assembled or may be assembled in variouscoacting relationships, and these include a housing generally indicatedby the reference character H (Figures 2, 3, 5, 6, 7 and 8) to which thethermostatic switch unit TS is initially assembled to form asub-assembly and a mounting plate generally indicated by the referencecharacter MP (Figures 4, 5, 6 and 7) with which the housing and switchsub-assembly is coactingly and selectively assembled and which can alsoserve as a cover or closure plate for the box B (Figures 4-7), beingperipherally shaped, illustratively circular, to suit the shape or openend of the box, being provided with sutiable means such as thediametrically opposed slot 24!- aud keyhole 25 (Figures 4 and 6) forcoaction with the screws 21-21 to secure it in position as a closingwall of the box B. The mounting plate MP is of suitably heavy metal,conveniently in the form of a stamping, and at a suitable locationtherein, preferably at its center, it is provided with a relativelylarge opening O, which may conveniently be punched therein in stampingout the plate itself and which is round or circular and of 'a diametermaterially greater than the outside diameter of the thermostatic diskassembly (see Figure 3), that being the outside diameter of the ferrulei3. Along `the line of the diameter of central'v opening O and as isbetter shown in Figures 4, 5 and 7, I provide, equally spaced from theopening O, threaded screw-receiving holes Zei-26.

The housing H (Figures l, 2, 3, 5, 6 and 8) is in the form of a moldingof cured plastic and hence insulating material and I provide it with afront Wall 27 that is externally ila-t and which, at its center, has around opening 28 (Figures 3 and 5) of a diameter slightly greater thatthe diameter of the ferrule i3 of the bimetallic disk assembly and,surrounding opening 28, is molded a collar C that projects from thefront wall 27 by an amount about equal to the thickness of the mountingplate MP s and that has substantial thicknessor radial dimension toprovide a large annular front face upon which, as'by printing ormolding, is carried and displayed suitable identifying or rating data asis diagrammatically indicated at 3i in Figures l, 4 and 6. The outsidediameter of collar C is such that the collar is relatively freelyreceivable into the opening O (see Figures 4 and 5) of the mountingplate MP with the hat front wall 27 of housing H resting atwise and wellseated against a face of the mounting plate MF.

As better shown in Figures 3 and 8, there are molded integrally with thefront wall 27 two relatively short pro- 'ections or pillars .3d-34closely adjacent the round Wall opening 2S and aligned along the line ofthe diameter of the latter; the sho-rt posts 3ft-34 provide inner flatfaces against which the opposed sheet-metal lugs 1515 of thethermostatic switch unit TS are brought to rest upon assembling thelatter to the housing H by moving it toward the right in Figure 3, toenter the switch casing into the housing opening 28, bringing the unitTS to rest with the plane of the bimetallic disk 12 parallel of thefront housing wall 27 but spaced forwardly therefrom and from the frontannular face of the coll-ar C, somewhat as shown in Figure 3. The shortposts 34-34 have molded into them the head ends of the two securing andconnecting screws 36,-36 over the threaded ends of which the aperturedconnector lugs -15 take during the above described assembly movement,whereupon the lugs 15S-15 are clamped against the posts 34-34 byclamping nuts 37-37, thus securing the therrnostatic switch unit TS inassembled relation to the housing H. The free threaded ends of thescrews 36-36 then receive suitable washers and nuts i3--4tlrespectively, whereby circuit conductors may be mechanically secured andthereby the switch mechanism ifi connected electrically into the systemcircuit.

The housing H has a side w-all 42 (Figures 3 and 5) which can be of anysuitable conguration preferably cylindrical (see Figure S), with itsaxis coincident with the axis of the front wall opening 23 (Figures 3and 5) and it extends rearwardly (to the left, in Figure 3) to terminatein an annular edge face 43 the plane of which is hat so that the housingmay rest well-seated against a face of the mounting plate MP as inFigure 7 or against some other flat supporting surface such as that of awall or ceiling or beam, indicated at 44, as shown in Figures l and 2.

The side wall l2 of housing H extends beyond the plane of the ends ofthe terminal screws 36-36 by a substantial amount (see Figure 3), inorder to provide ample space to removably receive a rear terminal coverplate TP of insulating material that is peripherally seated against aledge provided by the side wall 42 in the form of a rabbet 45 moldedinto the annular edge face 43 (Figures 3 and 8). With the side wall 42of annular cross-section, the rabbet 45 and the shoulders or ledge thatit forms are also circular and accordingly the terminal plate TP is inthe form of a disk of suitable insulating material, conveniently stampedout of flat stock, and in the course of so stamping it for peripheralreception in the rabbet 45, I also stamp out a central round hole 46(Figures 3, 8 and 9) that is of materially smaller diameter than theopening O in the mounting plate MP as is better shown in Figure 7, and lalso stamp or punch two smaller holes @f7-i7 (Figure 9) that are alignedon a diameter and equidistantly spaced from the center of the terminalplate TP.

Molded integrally with the front wall 27 of housing H (Figures 5, 7 and8) and projecting rearwardly therefrom are two pillars 48-43 aligned ona diameter of the housing H, a diameter that is at a right-angle to thediameter on which the short posts 35i-34 and their respective mountingand connecting screws .S6-36 are aligned; the pillars i3-48 terminate inend faces that fall in the plane of the casing rear edge face 43 (seeFigures 5 and 7), they are preferably of round cross-section, and attheir rear ends they are stepped to terminate in smallerdiarnetered endportions which extend respectively into the smaller holes 47-47 of theterminal cover plate TP and whereby also the pillars provide annularledges or seats 50-50 against which plate TP rests, coincidentally withits peripheral seating against the ledge of the rabbet 45 in the sidewall 42, as is better shown in Figure 7.

In each of the pillars 48-48, there is molded a coaxial hole 51 of adiameter to freely receive a screw therethrough, the hole 51terminating, at the front face of the front wall 27, in a largerdiameter, like a counterbore, as at 52 so as to accommodate therein thehead of a securing screw. The spacing, along the line of the diameter,of the axes of the long screw-receiving holes 51-51 is lthe same as thespacing, along the line of the diameter of the opening O in the mountingplate MP (see Figures 4, 5 and 7), of the threaded holes 26-26 in themounting plate MP. To selectively and coactingly assemble the mountingplate MP and the sub-assembly of housing H and thermostatic switch unitTS, I provide two machine screws 53--53 (see Figures 5 and 7).

Referring now to Figure 7, let it be assumed that, to meet one type ofwiring or installation requirement, a box B is required and that thesub-assembly of housing H and thermostatic switch unit TS have to be orcan be accommodated externally of the box B. ln such case, theappropriate insulated conductors, of which two are fragmentarily shownin Figure 7 at W-, are first brought through the large central opening 0in the mounting plate MP, either before or after securing the mountingplate iP in box-closing position by screws 21, the back terminal coverplate TP, detached from the housing H, is then snaked onto theconductors to pass them through the hole 46 which is smaller than themounting plate opening O and their stripped ends or portions are thenconnected respectively, by the washers 33 and nuts 4G, to the screwconnecting posts 36-36g housing H and insulating back plate TP are thenbrought together to seat the insulating plate in the peripheral wallrabbet 45 and against the annular shoulders or ledges Sti-S@ of theinternal pillars iS-48 respectively, and the resultant assemblage isthen brought against the front face of the mounting plate MP,substantially in the relationship shown in Figure 7; the machine screws53-53 are then inserted through the long holes Sl-S in the pilla-rs,from the front wall 27 of the housing H, and their threaded ends engagedrespectively with the threaded holes 26-26 of the mounting plate MP,thereby coaxially aligning the several coaxial parts of the sub-assemblywith the center or axis of the large opening O in the mounting plate MP,the heads of the screws being accommodated in the recesses 52-52 so thatthey do not protrude from the out side face of the front wall 27 ofhousing H.

The clamping pressure exerted by the screws 53 is taken up by therelatively heavy and strong illars di! (see Figure 7), protecting themolded non-metallic housing H against distortion and the housing H isheld wellseated against the front face of the metal mounting plate MPand the plane of the thermostatic disk element 12 is dependablypositioned to face in the desired direction such as downwardly from aceiling. Moreover, the rear insulating terminal cover plate T P, thoughnot directly secured to the rear of the housing H, becomes dependablylocked in piace to insulatingly close over the terminal connector screwsand the respective wiring connections made thereat, thus providing aninsulating barrier against the metal mounting plate MF, and the smallerhole te in the insulating plate TP becomes coaxially fixed relative tothe larger opening O of the mounting plate MP, as is better shown inFigure 7, thus to provide a protective insulating ring for the opening Oin the metal plate MP so that, for example, detrimental engagement ofthe insulated conductors W-l with the metal periphery of the opening Ois guarded against. And the rating. identifying, or other data thatappears on the front annular face of the collar C of the thermostaticswitch unit TS becomes positioned, as appears better from Figure 6,where it is indicated diagrammatically at 31, where it is always openingvisible.

in Figure 7 the box B is shown as surface-mounted, as by screws (notshown) or other suitable means, to the supporting surface of thebuilding part designated by the reference character 4d, such as aceiling, beam, or the like; it will be apparent, in View of thedisclosure herein, that the box B of Figure 7 may also be flushmountedor recessed into the ceiling or like structure, and in either case,where it is desired or appropriate to install the housing andthermostatic switch sub-assembly H-TS externally of the box, theassemblage thereof to the mounting plate MP is like that shown in Figure7 and may be proceeded with in the manner above described. However, ineither case and particularly where the box B is flush-mounted, it may bedesired or required that the sub-assembly be installed internally of thebox, particularly where, from the viewpoint of appearance, lessobtrusiveness is desired, and in such case the installation is effectedby re-arrangement of parts as is il'lustratively now to be described.

Such a rearrangement and different type of installation is illustratedin Figures 4 and 5, where the box is shown recessed in the ceiling 44 orlike support so that the plane of its open end is substanitally in theplane of the support. In this re-arrangement of the parts, theinsulating back terminal cover plate TP is removed from the back of thehousing7 H, and the latter, with the therinostatic switch unit TSassembled thereto to form the sub-assernbly as above described, isplaced with its flat front wall 27 against the inside face of themounting plate MP before the latter is secured to the box, positioningthe parts so that the thick-walled collar C enters the opening in themounting plate MP, thus permitting the flat front face of front wall 27to be seated atwise against the mounting plate and thus also, because ofthe intertitting of collar C with the plate opening O. aligning thevarious parts of the sub-assembly as a unit with the axis of the plateopening O. Thereby, by simple relative rotational movement, the holesSil-l of the internal pillars dii-4S are easily brought into respectivealignment with the threaded holes 26-26 of the metal mounting plate MP,whereupon the two machine screws E53-53 are inserted into the pillarholes through the rear end faces of the pillars and the threaded ends ofthe screws are then threaded into thel threaded holes 26-26 respectivelyas shown in Figure 5, with the screw heads taking against the rearannular end faces of the pillars which take up the clamping pressuresexerted by the screws, thus clamping and seating the front face of thefront wall 27 of the housing H snugly against the inside face of themounting plate MP, without detrimentally straining the housing H and thethermostatic switch ports carried thereby.

The circuit conductors (not shown) which can be like the conductors W-iof Figure 7, and which like the latter, are brought into the boxaccording to the particular type of circuit wiring desired or required,are now connected to the terminal connector screws E56-36 which, withtheir clamping washers and nuts, are readily accessible through the rearopen end of the housing H, because ot the absence of the rear insulatingterminal cover plate TP. The resultant assemblage is now as a unitattached to the box E, via the screws 21-21 and the slots 24;--25 (seeFigures 4 and 5) with the open-ended sub-assembly of thermostatic switchunit TS and housing H carried und positioned inside of the now coveredor closed-over box E, except for the collar C and the bimetallic disk 12and part of the securing ferrule 13 which extend within and slightlybeyond the collar C, somewhat as shown in Figure 5. The plane of thefront face of the mounting plate MP can be coincident with the surfaceof the plete installation.

ceiling 44 and both surfaces can be painted or finished oi so that onevirtually merges into the other.

Only the bimetallic disk 12 and part of its securing ferrule 13 projectsomewhat beyond the outer face of "ie mounting plate MP and thebimetallic disk 12 is dependably positioned facing the area or space tothe temperature of which it is to respond upon dangerous rise;surrounding it and the ferrule 13 is the non-metallic collar C of thehousing H, being in effect interposed therebetween and the metalmounting plate MP to vir tuaily form a barrier against the drainage ofheat away from the bimetallic disk by the surrounding mounting platemetal that has much greater mass and area, thus avoiding detrimentalinterference with the sensitiveness of temperature response of thebimetallic disk itself. At the saine time, the front annular andradially-wide face of the collar C is fixedly positioned and itsidentifying, rating, or other data 31 (see Figure 4) carried by it isdependably maintained visible at the front of the com- It will now bereadily apparent, in view of the foregoing, that the installation justdescribed, with the sub-assembly of thermostatic switch unit TS Iandhousing H positioned inside of the box B, may be carried out with equaleffectiveness in meeting various requirements or standards of safetywiring where the box B is surface-mounted as is the box B of Figure 7.

As earlier above noted, where the fire alarm or detection systemoperates at relatively low voltages, it is permissible to employsuitably insulated conductors that may be run along and secured to theexposed surfaces of ceilings, beams, or the like, and in such cases itis permissible to install the thermostatic switch unit on such surfaceswithout the intervention of special wiring accessories, such as outletboxes or the like, as are required for higher-Voltage systems. ln suchcases, I make provision in Athe housing H for mounting it, with itsthereto assembled thermostatic switch unit TS, directly to and upon suchsurface and for ease and facility of leading the insulated wires to theinterior of the housing and at the same time protectively insulating theceiling or other surfaces from the interior terminal connectors andconnections. As is better shown in Figure 3 and also in Figure S, Iprovide, by molding, two cut-outs S23- 55 in the side wall 42 of housingH and at diametrically 0pposed points therein along the line of thediameter along which are located the terminal screws Zio-36; thesecutouts are open ended into the rear edge face 43 of the peripheral sidewall 42 of the housing H.

By removing the insulating back cover plate TP, the circuit wires arereadily connected to the terminal screws and then they are laid intoeither or both of the openended cut-outs 55, that being facilitated bythe diametrical alignment (see Figure 8) of the cut-outs and terminalconnectors and by the roominess within the housing H inasmuch as thepillars 4848 are located well to either side of such diametricalalignment of these parts and, as is better shown in Figure 3, thethermostatic switch casing 10 projects but slightly into the interior ofhousing H. For similar reason of roominess, it might be here noted, theelectrical connections necessary in completing the other types ofinstallations above described in connection with Figures 4 5 and Figures6-7 are made with equal facility even though the parts are relativelysmall.

For direct surface-installation, having laid the insu lated wires in thecut-outs 555-55, the rear insulating terminal cover TP is put in place,being peripherally seated in the rabbet 45 only when the plate TP isrotatively positioned so that its two spaced small holes 47-47 (seeFigure 9 and Figure 8) are coaxial with the pillars 3S-43 respectivelyto enter the smaller-diametered ends of the pillars 48-48 into therespective plate holes 417-47. Now, wood screws 56 are entered throughthe holes 51h51 of these pillars, through the front face of front wall27, and with the back plate TP assembled as just described, it is notneces ary to have to manipulate the back plate to seek out holes orpassages therein through which the screws are to pass. in this manner,the mounting of the sub-assembly directly to the surface of the ceilingor other support, indicated at 44 in Figures l, 2 and 3, is readilycompleted with the driving home of the screws Se Se, the heads of whichenter the recesses at the outer ends of the pillar holes Si and therebythe housing H is securely clamped to the supporting surface, with theotherwise unsecured insulating bachr plate 'P locked in closing positionand safely insulating the terminal connectors and electrical connectionsthereat from the supporting surface dei. The screw clamping stresses aretaken up primarily by the relatively heavy pillars ifi-d3 withoutdetrimentally straining the non-metallic insulating housing H.

The bimetallic disk element it?. is thus dependa-bly installed andpositioned in relation to the room or to the temperature of which it isto respond upon dangerous rise; the collar C, surrounding it with itsbroad annular front face, maintains visible the desired or requiredidentifying, rating or other data thereon, indicated at 31 in Figure l,in this type of direct-surface installation.

It will be seen that there has been provided in this invention, atemperature-responsive electric switch and housing, mounting andinstallation in which the several objects hereinabove set forth,together with many theroughly practical advantages, are successfullyachieved. It will be seen that the constructions are capable of ease offabrication and provide wide and dependable llexibility of assembly, inthe held, to reliably meet varying conditions and requirements met withparticularly in the wiring and installation of tire alarm or detectorsystems in the various types of house or building construction met with.

As many possible embodiments may be made of the above invention and asmany changes might be made in the embodiments above set forth, it is tobe understood that all matter hereinabove set forth or shown in theaccompanying drawings is to be interpreted as illustrative and not in alimiting sense.

I claim:

l. A thermostatic switch mounting means comprising a mounting platehaving a relatively large round opening therein with threaded screwholes spaced therefrom and adapted to form a closure for an outlet box,a housing of insulating material having a front wall provided with anaperture surrounded by a collar, said collar having an outside diameterso that it is receivable in said mounting plate opening, a thermostaticswitch structure supported within said housing and having a partcomprising a bimetallic disk positioned to substantially close ott saidaperture at said collar, said switch structure having ter minalconnectors within said housing, said housing having a peripheral sidewall and a rear closure plate ot' insulating material and removablyassociated therewith, said rear closure plate having a relatively largeround opening therein that is smaller than the opening in said mountingplate and that is coaxial with said collar, said housing and rearclosure plate having means forming spaced screw passages of the samespacing as the threaded holes in said mounting plate, and threadedscrews to extend through said passages for threading into said threadedholes from the rear end of said housing with the tro-nt wall of thelatter resting against the inside face ot said mounting plate and saidcollar received in the mounting plate opening or from the front wallwith said rear closure plate resting against the outside face of saidmounting plate and with the smaller opening in said insulating rearclosing plate substantially coaxial with the larger opening in saidmounting plate to substantially peripherally insulate the latter openingfor the passage of connecting conductors therethrough to said connectingterminals.

2. A thermostatic switch mounting means comprising a mounting platehaving a relatively large round opening therein with threaded screwholes spaced therefrom and adapted to form a closure for .an outlet box,a housing of insulating material having a front wall provided with anaperture surrounded by a collar, said collar having an outside diameterso that it is receivable in said mounting plate opening, a thermostaticswitch structure supportedwithin said housing and having a partcomprising a bimetallic disk positioned to substantially close olf saidaperture at said collar, said switch structure having terminalconnectors within said housing, said housing having peripheral sidewalls terminating in a rabbeted rear edge face and said front wallhaving spaced hollow pillars extending rearwardly therefrom andterminating in the plane of said rear edge face, a rear cover plate ofinsulating material peripherally seated removably in the rabbet ot saidrear edge face and having cut-outs to clear said hollow pillars, saidcover plate having a round opening smaller than that of said mountingplate and coaxial with said collar, and threaded screws for threadedengagement with said spaced threaded holes in the mounting plate uponpassage of the screws from the rear ends 0f said pillars with the frontwall resting against the inside face of said mounting plate and saidcollar entered into said mounting plate opening or for passage into saidpillars from the front wall of the housing with said rear edge face andinsulating rear cover plate resting against the outside face of themounting plate with said two plate openings substantially coaxial sothat the mounting plate opening is peripherally insulatingly overlapped.

3. A thermostatic switch mounting means comprising a mounting platehaving a relatively large round opening therein with threaded screwholes spaced therefrom and adapted to form a closure 'for an outlet box,a housing of insulating material having a front wall provided with anaperture surrounded by a collar, said collar having an outside diameterdimensioned so that it is receivable in said mounting plate opening, athermostatic switch `structure supported from within said housing andextending into the space encompassed by said collar and positioning tothe exterior of said space a thermally-responsive element, said switchstructure having terminal connectors underlying said front wall at theside of said aperture, said housing having peripheral shallow side wallsIterminating in a rear edge face and said front wall having spacedhollow pillars of the same spacing as said threaded holes and extendingrearwardly and terminating in lthe plane of said rear edge face, saidside walls and said pillars having ledges that lie internally of saidplane, a rear `cover plate of insulating material seated removably atsaid ledges of said side walls and having spaced holes to receive therear-ends of said pillars up to the ledges of the latter, said coverplate having a round opening smaller than that of said mounting plateand coaxial with said collar, and threaded screws for threadedengagement with said spaced threaded holes in the mounting plate uponpassage of the screws from the rear ends of said hollow pillars with thefront wall resting against -the inside face ot' said mounting plate andsaid collar entered into said mounting plate opening or for passage intosaid pillars from the front Wall of the housing with said rear edge faceand the rear ends of said pillars resting against the outside face ofthe mounting plate with the insulating cover plate between said outsideface and said ledges and said two plate openings substantially coaxialso that the mounting plate opening is peripherally insulatinglyoverlapped.

4. A thermostatic switch and housing means for selective mounting by amounting plate that has a relatively large round opening therein withthreaded screw holes spaced ytherefrom and adapted to form a closure foran outlet box, said means comprising a housing of insulating materialhaving a front wall provided with a round aperture surrounded by acollar of substantial radial dimension and presenting a relatively largeannular front face for identifying rating indicia, a thermostatic switchstructure supported from within said housing and extending into thespace encompassed by said collar and positioning to the exterior abimetallic disc corresponding to said rating indicia, said switchstructure having terminal connectors within said housing, said housinghaving a peripheral side wall and a rear `cover plate of insulatingmaterial removably associated therewith, said rear cover plat-e having arelatively large round lopening therein that is coaxial wi-th saidcollar, said housing and rear closure plate having means forming spacedscrew passages from front to rear for the passage therethrough ofmounting screws and whereby threaded screws may be extended through saidpassages for threading into said threaded holes from the rear of saidhousing with the front wall of the latter resting against the insideface of said mounting plate and said collar with its rating indiciareceived in the mounting plate opening and the indicia maintained`visible or said screws extended therethrough from 'the fron-t wall withsaid rear cover plate adjacent the outside face of said mounting plateand wi-th the opening in said insulating rear cover plate substantiallycoaxial with the opening in said mounting plate for `the passage ofconnecting conductors therethrough to said connecting termin-als.

5. A thermostatic switch and housing means for selective surfacemounting or mounting by a mounting plate that. has a relatively largeround opening therein with threaded screw holes spaced therefrom andadapted to form a closure for an outlet box, said means comprising ahousing of insulating material having a front wall provided with a roundaperture surrounded by a collar of substantial radial dimension andpresenting `a relatively large annular front face for identifying ratingindicia, a thermostatic switch structure supported from within saidhousing and extending into lthe space encompassed by said collar `andpositioning to the exterior a bimetallic disc corresponding to saidrating indicia, said switch structure having terminal connectors withinsaid housing, said housing 'having a peripheral side wall and a rearcover plate of insulating material removably associated therewith, saidhousing and rear closure plate having means forming spaced screwpassages from front to rear for the passage therethrough of mountingscrews and whereby threaded screws may be extended through said passagesfor threading into said threaded holes from the rear of said housingwith the front wall of the latter resting against the inside face ofsaid mounting plate and said collar with its rating indicia received inthe mounting plate 'opening and the indicia maintained visible or screwsmay be extended therethrough from the front wall with said rear coverplate adjacent the surface of a support and locked between the latterand the housing upon threading the screws into said support and saidcollar and rating indicia thereby `faced forwardly of said supportingsurface.

6. A thermostatic switch and housing means for selective surfacemounting or mounting by a mounting plate that has a relatively largeround opening therein with threaded screw holes spaced about a circleyconcentric with said opening, said plate being adapted to form aclosure for an outlet box, said means comprising a housing of insulatingmaterial having a front wall provided with a round aperture ofmaterially smaller diameter ythan that oi' said plate opening andbearing identifying rating indicia within an exterior `annular areaabout the aperture of radial dimension not greater than the differencein the radii of said opening and aperture, a thermostatic switchstructure supported from within said housing and extending into saidround aperture and positioning to the exterior of the housing andcoaxially with said annular area a bimetallic disc corresponding to saidrating indicia, said switch structure terminal connectors Within saidl'tousing, said housing having a peripheral side wall and a rear coverplate of insulating material removably associated therewith, saidhousing and rear closure plate having means forming screw passages fromfront to rear for the passage therethrough of mounting screws, saidscrew passages being spaced about a circle concentric with said annularindicia-bearing area and of the same diameter as the circular of spacingof said threaded screw holes of the mounting plate, whereby threadedscrews may be extended lthrough said passages for threading into saidthreaded holes from the rear of said housing with the front wall of thelatter resting against the inside face of said mounting plate and saidannular indicia-bearing area located coaxially with the mounting plateopening to fall within the projected area of |the latter and the indiciamaintained visible or screws may be extended therethrough from the frontWall with said rear cover plate adjacent the surface of a support andlocked between the latter and the housing upon threading the screws intosaid support and said annular area and rating indicia thereby facedforwardly of said supporting surface.

7. A thermostatic switch and housing means comprising a housing ofinsulating material having a front wall provided with an aperturesurrounded by an external collar of relatively substantial radial andaxial extent, a thermostatic switch structure supported from within saidhousing and extending into the space encompassed by said collar andpositioning to the exterior of said space a thermally-responsiveelement, said switch structure having terminal connectors underlyingsaid front wall at the side of said aperture, said housing havingperipheral shallow side walls terminating in a rear edge face and saidfront wall having spaced hollow pillars extending rearwardly andterminating in the plane of said rear edge face, said side walls andsaid pillars having ledges that lie inwardly of said plane, a rear coverplate of insulating material seated removably at said ledges of saidside walls and having spaced holes to receive the rear ends of saidpillars up to the ledges of the latter, said rear cover plate having around opening that is coaxial with said collar, and threaded screws forpassage through said hollow pillars to secure said housing to a supportand adapted when passed into said pillars from the front of the housingwith the rear ends of said pillars resting against a supporting surfaceto clamp the pillars against the latter `with the insulating cover platelocked between said supporting surface and said ledges.

8. A thermostatic switch and housing means comprising a housing ofinsulating material having a front wall provided with a central roundaperture with two connector screws depending interiorly fromdiametrically opposed short posts formed in said wall, a thermostaticswitch structure extending into said aperture and positioning to theexterior of said housing a thermally-responsive element, said switchstructure having diametrically opposed connector lugs underlying saidfront wall and respectively secured to said screws, said housing havinga peripheral cylindrical side wall terminating in a rear edge face andsaid front wall having two hollow pillars spaced on a diameter making anangle to the diameter on which lie said spaced connector screws, saidpillars extending rearwardly and terminating in the plane of said rearedge face, said side wall having ledges that lie inwardly of said plane,a disk-like rear cover plate of insulating material seated removably atsaid ledges of said wall and having spaced holes to receive the rearends of said pillars whereby said cover plate cannot be seated at saidledges unless it is rotatively oriented to enter the pillar ends in itsholes, and threaded screws for passage through said hollow pillars tosecure said housing to a support and adapted when passed into saidpillars from the front of the housing with the rear ends of said pillarsresting against a supporting surface to clamp the pillars against thelatter with the insulating cover plate locked between said supportingsurface and said ledges.

No references cited.

